Stress corrosion cracking of Zr-H alloy in iodine environment

The behavior of stress corrosion cracking of Zr-H alloys irradiated with neutrons was examined by SERT method. The specimens of Zr metal and Zr-H alloy were irradiated with the neutron fluence of 1.2 x 1020 n/cm2 (E > 1 MeV) at the temperature from 150 to 183 deg C in the Japanese Material Testing Reactor (JMTR). After the irradiation, tensile test at room temperature was performed in the atmosphere and in the methyl alcohol solution containing 1 wt.% iodine. Due to the fast-neutron irradiation, the elongation of the Zr metal decreased remarkably, and no elongation was observed in the irradiated Zr-H alloy. The neutron irradiation also accelerated the decrease of the elongation of the Zr metal in the iodine environment rather than in the atmosphere. The relation between the yield stress or the tensile strength vs. strain rate in the Zr metal and the relation between the maximum stress vs. strain rate in the Zr-H alloy were examined for the irradiated and unirradiated specimens and in the atmosphere and the iodine environment. (Asami, T.)